I have a simple application that takes user input by text and time
selected by date time picker. It displays the appt description in one
list box and the time in another list box. I have a simple function
that checks the times for duplicates. I want to check for a duplicate
before it writes to the listbox by returning a boolean (true/false)
value. I only need to check hours and minutes not date or seconds.

Right now I have this but it's not finding duplicates, I think there's
a problem with the function? Any Suggestions?

Dim Time As Boolean

Time = TimeTaken(Me.dtmTime.Value.ToShort* DateString)

If Time Then
MessageBox.Show("You already have an appointment at
this time")
Else

'display appointment in Listbox
lstApptResults.Items.Add(txtAppoin* tment.Text)
txtAppointment.Clear() 'clear appointment from TextBox
txtAppointment.Focus() 'transfer focus to TextBox

'display appointment time in Listbox

lstTimeResults.Items.Add(Me.dtmTim* e.Value.ToShortTimeString)

End If
End If
End Sub 'btnAddAppt_Click
'function to check if an appointment time already exists in listbox
Public Function TimeTaken(ByVal ApptTime As DateTime) As Boolean

Dim DuplicateTime As Boolean = False

'loop that checks listed times for duplicates
For Each strItem As String In lstTimeResults.Items
If strItem = ApptTime Then
DuplicateTime = True

Exit For
End If
Next

Return DuplicateTime
End Function 'TimeTaken